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SSC CHSL 2021 PYQ — Question 66

SSC CHSL - 15 April 2021 - Shift 2 • Quantitative Aptitude • Q66

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If (3p - 5m) = 5 and pm = 6, then what is the value of (9p2 - 25m2)?

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Correct answer: D

Explanation

The correct answer is option 4 i.e.  ±5385\pm5\sqrt{385}

(3p - 5m)2 = 9p2 + 25m2 - 30pm

⇒ 25 = 9p2 + 25m2 - 180

⇒ 9p2 + 25m2 = 205

Then,

⇒ (3p + 5m)2 = 9p2 + 25m2 + 30pm

⇒ (3p + 5m) = ±√385

⇒ (9p2 - 25m2) = (3p - 5m)(3p + 5m)

= ±5√385